Magnetic recording devices having negative polarization layer to enhance spin-transfer torque

ABSTRACT

Aspects of the present disclosure generally relate to a magnetic recording head of a spintronic device, such as a write head of a data storage device, for example a magnetic media drive. In one example, a magnetic recording head includes a main pole, a trailing shield, and a spin torque layer (STL) between the main pole and the trailing shield. The magnetic recording head includes a first layer structure on the main pole, and the first layer structure includes a negative polarization layer. The magnetic recording head also includes a second layer structure disposed on the negative polarization layer and between the negative polarization layer and the STL. The negative polarization layer is an FeCr layer. The second layer structure includes a Cr layer disposed on the FeCr layer, and a Cu layer disposed on the Cr layer and between the Cr layer and the STL.

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

Aspects of the present disclosure generally relate to a magneticrecording head of a spintronic device, such as a write head of a datastorage device, for example a magnetic media drive.

Description of the Related Art

The heart of the functioning and capability of a computer is the storingand writing of data to a data storage device, such as a hard disk drive(HDD). The volume of data processed by a computer is increasing rapidly.There is a need for higher recording density of a magnetic recordingmedium to increase the function and the capability of a computer.

In order to achieve higher recording densities, such as recordingdensities exceeding 2 Tbit/in² for a magnetic recording medium, thewidth and pitch of write tracks are narrowed, and thus the correspondingmagnetically recorded bits encoded in each write track is narrowed. Onechallenge in narrowing the width and pitch of write tracks is decreasinga surface area of a main pole of the magnetic write head at a mediafacing surface. As the main pole becomes smaller, the writing fieldbecomes smaller as well, limiting the effectiveness of the magneticwrite head.

Heat-assisted magnetic recording (HAMR) and microwave-assisted magneticrecording (MAMR) are two types of energy-assisted recording technologyto improve the recording density of a magnetic recording medium, such asa HDD. In MAMR, a spin torque oscillator (STO) device is located next toor near the write element in order to produce a high-frequency AC field,such as in a microwave frequency band. The high-frequency AC fieldreduces an effective coercivity of a magnetic recording medium used tostore data and allows writing of the magnetic recording medium at lowermagnetic writing fields emanated from the write pole. Thus, higherrecording density of the magnetic recording medium may be achieved byMAMR technology.

Energy-assisted recording write heads may require an undesirable highvoltage and/or an undesirable high current to produce a write fieldenhancement. A high voltage and/or high current may impact the lifetimeand the reliability of the write head by degrading components of thewrite head. Lowering the voltage, moment-thickness product of theenergy-assist magnetic layer, or the current can hinder writerperformance, lower areal density capability (ADC), and/or limit thematerials used in write heads.

Therefore, there is a need for write heads that simply and effectivelyfacilitate write head performance reliability and high moment-thicknessproduct of the energy-assist magnetic layer while facilitating lowervoltage or current to facilitate effective and efficient magneticrecording, and high ADC of magnetic recording.

SUMMARY OF THE DISCLOSURE

Aspects of the present disclosure generally relate to a magneticrecording head of a spintronic device, such as a write head of a datastorage device, for example a magnetic media drive. In one example, amagnetic recording head includes a main pole, a trailing shield, and aspin torque layer (STL) between the main pole and the trailing shieldthat provides energy-assisted write field enhancement. The magneticrecording head includes a first layer structure on the main pole, andthe first layer structure includes a negative polarization layer. Themagnetic recording head also includes a second layer structure disposedon the negative polarization layer and between the negative polarizationlayer and the STL. The negative polarization layer is an FeCr layer. Thesecond layer structure includes a Cr layer disposed on the FeCr layer,and a Cu layer disposed on the Cr layer and between the Cr layer and theSTL.

In one implementation, a magnetic recording head includes a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and a first spacer layer between the STL and thetrailing shield. The magnetic recording head also includes a multilayerstructure disposed on the main pole and between the main pole and theSTL. The multilayer structure includes a first layer structure on themain pole. The first layer structure includes a negative polarizationlayer. The multilayer structure also includes a second layer structuredisposed on the negative polarization layer and between the negativepolarization layer and the STL.

In one implementation, a magnetic recording head includes a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and a multilayer structure disposed on the main poleand between the main pole and the STL. The multilayer structure includesan FeCr layer between the main pole and the STL, a Cr layer disposed onthe FeCr layer, and a Cu layer disposed on the Cr layer and between theCr layer and the STL.

In one implementation, a magnetic recording head includes a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and at least one negative polarization layer betweenthe main pole and the STL. The at least one negative polarization layerincludes a magnetic material.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a schematic illustration of a magnetic recording device,according to one implementation.

FIG. 2 is a schematic illustration of a cross sectional side view of ahead assembly facing the magnetic disk shown in FIG. 1 or other magneticstorage medium, according to one implementation.

FIG. 3A is a schematic illustration of a plan view of an MFS of thewrite head shown in FIG. 2, according to one implementation.

FIG. 3B is a schematic illustration of a plan view of an MFS of thewrite head shown in FIG. 2, according to one implementation.

FIG. 4 is a schematic illustration of a cross-sectional throat view ofthe spintronic device of the write head shown in FIG. 3A, according toone implementation.

FIG. 5 is a schematic graphical illustration of calculated torque of anSTL versus an angle of magnetization for the STL, according to oneimplementation.

FIG. 6 is a schematic graphical illustration of an angle ofmagnetization for the STL versus applied current density, according toone implementation.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

In the following, reference is made to embodiments of the disclosure.However, it should be understood that the disclosure is not limited tospecific described embodiments. Instead, any combination of thefollowing features and elements, whether related to differentembodiments or not, is contemplated to implement and practice thedisclosure. Furthermore, although embodiments of the disclosure mayachieve advantages over other possible solutions and/or over the priorart, whether or not a particular advantage is achieved by a givenembodiment is not limiting of the disclosure. Thus, the followingaspects, features, embodiments and advantages are merely illustrativeand are not considered elements or limitations of the appended claimsexcept where explicitly recited in a claim(s). Likewise, reference to“the disclosure” shall not be construed as a generalization of anyinventive subject matter disclosed herein and shall not be considered tobe an element or limitation of the appended claims except whereexplicitly recited in a claim(s).

Aspects of the present disclosure generally relate to a magneticrecording head of a spintronic device, such as a write head of a datastorage device, for example a magnetic media drive. In one example, amagnetic recording head includes a main pole, a trailing shield, and aspin torque layer (STL) between the main pole and the trailing shield.The magnetic recording head includes a first layer structure on the mainpole, and the first layer structure includes a negative polarizationlayer. The magnetic recording head also includes a second layerstructure disposed on the negative polarization layer and between thenegative polarization layer and the STL. The negative polarization layeris an FeCr layer. The second layer structure includes a Cr layerdisposed on the FeCr layer, and a Cu layer disposed on the Cr layer andbetween the Cr layer and the STL.

FIG. 1 is a schematic illustration of a magnetic recording device 100,according to one implementation. The magnetic recording device 100includes a magnetic recording head, such as a write head. The magneticrecording device 100 is a magnetic media drive, such as a hard diskdrive (HDD). Such magnetic media drives may be a single drive/device orinclude multiple drives/devices. For the ease of illustration, a singledisk drive is shown as the magnetic recording device 100 in theimplementation illustrated in FIG. 1. The magnet recording device 100(e.g., a disk drive) includes at least one rotatable magnetic disk 112supported on a spindle 114 and rotated by a drive motor 118. Themagnetic recording on each rotatable magnetic disk 112 is in the form ofany suitable patterns of data tracks, such as annular patterns ofconcentric data tracks on the rotatable magnetic disk 112.

At least one slider 113 is positioned near the rotatable magnetic disk112. Each slider 113 supports a head assembly 121. The head assembly 121includes one or more magnetic recording heads (such as read/writeheads), such as a write head including a spintronic device. As therotatable magnetic disk 112 rotates, the slider 113 moves radially inand out over the disk surface 122 so that the head assembly 121 mayaccess different tracks of the rotatable magnetic disk 112 where desireddata are written. Each slider 113 is attached to an actuator arm 119 byway of a suspension 115. The suspension 115 provides a slight springforce which biases the slider 113 toward the disk surface 122. Eachactuator arm 119 is attached to an actuator 127. The actuator 127 asshown in FIG. 1 may be a voice coil motor (VCM). The VCM includes a coilmovable within a fixed magnetic field, the direction and speed of thecoil movements being controlled by the motor current signals supplied bya control unit 129.

The head assembly 121, such as a write head of the head assembly 121,includes a media facing surface (MFS) such as an air bearing surface(ABS) that faces the disk surface 122. During operation of the magneticrecording device 100, the rotation of the rotatable magnetic disk 112generates an air or gas bearing between the slider 113 and the disksurface 122 which exerts an upward force or lift on the slider 113. Theair or gas bearing thus counter-balances the slight spring force ofsuspension 115 and supports the slider 113 off and slightly above thedisk surface 122 by a small, substantially constant spacing duringoperation.

The various components of the magnetic recording device 100 arecontrolled in operation by control signals generated by control unit129, such as access control signals and internal clock signals. Thecontrol unit 129 includes logic control circuits, storage means and amicroprocessor. The control unit 129 generates control signals tocontrol various system operations such as drive motor control signals ona line 123 and head position and seek control signals on a line 128. Thecontrol signals on line 128 provide the desired current profiles tooptimally move and position slider 113 to the desired data track onrotatable magnetic disk 112. Write and read signals are communicated toand from the head assembly 121 by way of recording channel 125. In oneembodiment, which can be combined with other embodiments, the magneticrecording device 100 may further include a plurality of media, or disks,a plurality of actuators, and/or a plurality number of sliders.

FIG. 2 is a schematic illustration of a cross sectional side view of ahead assembly 200 facing the rotatable magnetic disk 112 shown in FIG. 1or other magnetic storage medium, according to one implementation. Thehead assembly 200 may correspond to the head assembly 121 described inFIG. 1. The head assembly 200 includes a media facing surface (MFS) 212,such as an air bearing surface (ABS), facing the rotatable magnetic disk112. As shown in FIG. 2, the rotatable magnetic disk 112 relativelymoves in the direction indicated by the arrow 232 and the head assembly200 relatively moves in the direction indicated by the arrow 233.

In one embodiment, which can be combined with other embodiments, thehead assembly 200 includes a magnetic read head 211. The magnetic readhead 211 may include a sensing element 204 disposed between shields S1and S2. The sensing element 204 is a magnetoresistive (MR) sensingelement, such an element exerting a tunneling magneto-resistive (TMR)effect, a magneto-resistance (GMR) effect, an extraordinarymagneto-Resistive (EMR) effect, or a spin torque oscillator (STO)effect. The magnetic fields of magnetized regions in the rotatablemagnetic disk 112, such as perpendicular recorded bits or longitudinalrecorded bits, are detectable by the sensing element 204 as the recordedbits.

The head assembly 200 includes a write head 210. In one embodiment,which can be combined with other embodiments, the write head 210includes a main pole 220, a leading shield 206, a trailing shield (TS)240, and a spintronic device 230 disposed between the main pole 220 andthe TS 240. The main pole 220 serves as a first electrode. Each of themain pole 220, the spintronic device 230, the leading shield 206, andthe trailing shield (TS) 240 has a front portion at the MFS.

The main pole 220 includes a magnetic material, such as CoFe, CoFeNi, orFeNi, other suitable magnetic materials. In one embodiment, which can becombined with other embodiments, the main pole 220 includes small grainsof magnetic materials in a random texture, such as body-centered cubic(BCC) materials formed in a random texture. In one example, a randomtexture of the main pole 220 is formed by electrodeposition. The writehead 210 includes a coil 218 around the main pole 220 that excites themain pole 220 to produce a writing magnetic field for affecting amagnetic recording medium of the rotatable magnetic disk 112. The coil218 may be a helical structure or one or more sets of pancakestructures.

In one embodiment, which can be combined with other embodiments, themain pole 220 includes a trailing taper 242 and a leading taper 244. Thetrailing taper 242 extends from a location recessed from the MFS 212 tothe MFS 212. The leading taper 244 extends from a location recessed fromthe MFS 212 to the MFS 212. The trailing taper 242 and the leading taper244 may have the same degree or different degree of taper with respectto a longitudinal axis 260 of the main pole 220. In one embodiment,which can be combined with other embodiments, the main pole 220 does notinclude the trailing taper 242 and the leading taper 244. In such anembodiment, the main pole 220 includes a trailing side and a leadingside in which the trailing side and the leading side are substantiallyparallel.

The TS 240 includes a magnetic material, such as FeNi, or other suitablemagnetic materials, serving as a second electrode and return pole forthe main pole 220. The leading shield 206 may provide electromagneticshielding and is separated from the main pole 220 by a leading gap 254.

The spintronic device 230 is positioned proximate the main pole 220 andreduces the coercive force of the magnetic recording medium, so thatsmaller writing fields can be used to record data. An electron currentis applied to spintronic device 230 from a current source 270 to producea microwave field. The electron current may include direct current (DC)waveforms, pulsed DC waveforms, and/or pulsed current waveforms going topositive and negative voltages, or other suitable waveforms.

In one embodiment, which can be combined with other embodiments, thespintronic device 230 is electrically coupled to the main pole 220 andthe TS 240. The main pole 220 and the TS 240 are separated in an area byan insulating layer 272. The current source 270 may provide electroncurrent to the spintronic device 230 through the main pole 220 and theTS 240. For direct current or pulsed current, the current source 270 mayflow electron current from the main pole 220 through the spintronicdevice 230 to the TS 240 or may flow electron current from the TS 240through the spintronic device 230 to the main pole 220 depending on theorientation of the spintronic device 230. In one embodiment, which canbe combined with other embodiments, the spintronic device 230 is coupledto electrical leads providing an electron current other than from themain pole 220 and/or the TS 240.

FIG. 3A is a schematic illustration of a plan view of an MFS of thewrite head 210 shown in FIG. 2, according to one implementation. Thewrite head 210 includes a spintronic device 330 between the main pole220 and the TS 240 in the track direction. The spintronic device 330 maybe used as the spintronic device 230 shown in FIG. 2.

It is to be understood that the magnetic recording head discussed hereinis applicable to a data storage device such as a hard disk drive (HDD)as well as a tape drive such as a tape embedded drive (TED) or aninsertable tape media drive. An example TED is described in co-pendingpatent application titled “Tape Embedded Drive,” U.S. application Ser.No. 16/365,034, filed Mar. 31, 2019, assigned to the same assignee ofthis application, which is herein incorporated by reference. As such,any reference in the detailed description to a HDD or tape drive ismerely for exemplification purposes and is not intended to limit thedisclosure unless explicitly claimed. Furthermore, reference to orclaims directed to magnetic recording devices are intended to includeboth HDD and tape drive unless HDD or tape drive devices are explicitlyclaimed.

It is also to be understood that aspects disclosed herein, such as themagnetic recording heads, may be used in magnetic sensor applicationsoutside of HDD's and tape media drives such as TED's, such as spintronicdevices other than HDD's and tape media drives. As an example, aspectsdisclosed herein may be used in magnetic elements in magnetoresistiverandom-access memory (MRAM) devices (e.g., magnetic tunnel junctions aspart of memory elements), magnetic sensors or other spintronic devices.

The spintronic device 330 uses spin-transfer torque (STT) to facilitatemagnetic recording. The present disclosure contemplates that thespintronic device 330 may be used with spin-orbital torque (SOT).

The spintronic device 330 includes a multilayer structure 310 disposedon the main pole 220, a spin torque layer 320 (STL), and a first spacerlayer 390. In one embodiment, which can be combined with otherembodiments, the STL 320 is a spin polarization layer (SPL) or a spinpolarizing layer. The sides of the spintronic device 330 at the MFS areion milled or patterned, for example, to form the spintronic deviceshape as shown. The multilayer structure 310 is disposed between and incontact with the main pole 220 and the STL 320. The multilayer structure310 is between the main pole 220 and the trailing shield 240. Themultilayer structure 310 is used in place of a seed layer disposed onthe main pole 220. The first spacer layer 390 is between the STL 320 andthe trailing shield 240. A TS hot seed layer 380 is over the firstspacer layer 390. The TS hot seed layer 380 is magnetically stitchedwith a notch of the TS 240.

A current source 270 is configured to supply a current to the spintronicdevice 330. The current supplied using the current source 270facilitates an electron flow from the main pole 220 through thespintronic device 330 to the TS 240. The direction of the currentsupplied through the spintronic device 330 is opposite of the directionof the electron flow through the spintronic device 330. Polarizedelectrons from the STL 320 are reflected off from a first interface 301between the TS 240 and the first spacer layer 390, such as between theTS hot seed layer 380 and the first spacer layer 390, back toward theSTL 320. Spin accumulation and spin torque occurs at a second interface302 between the first spacer layer 390 and the STL 320.

The STL 320 is initially magnetized in the same direction asmagnetization of the main pole 220 and the TS 240, which is in adirection from the main pole 220 to the TS 240 and is in the samedirection as the electron flow. The spin torque acts on the STL 320causing spin flipping of the STL 320 and precession of magnetization Mof the STL 320. Precession of the magnetization M of the STL 320 cangenerate an assisting magnetic field, such as a DC field, emitted to amagnetic recording medium. The assisting magnetic field reduces thecoercive force of the recording medium and enhances the write field fromthe main pole 220 to write to the recording medium.

The bias voltage (Vjump) at which spin flipping occurs is estimatedaccording to formula (1):Vjump=J _(c) *RA  (1)in which J_(c) is the critical current density for STT switching againstthe gap field.

The multilayer structure 310 includes a first layer structure 311 on themain pole 220 and a second layer structure 314 on the first layerstructure 311. The spintronic device includes at least one negativepolarization layer (NPL) 312. The second layer structure 314 is betweenthe first layer structure 311 and the STL 320, and is in contact withthe first layer structure 311 and the STL 320. The first layer structure311 includes the negative polarization layer (NPL) 312. The negativepolarization layer 312 is magnetic and includes a magnetic material, andis magnetized in the same direction as the main pole 220 and theelectron flow. In one embodiment, which can be combined with otherembodiments, the first layer structure 311 is a monolayer including thenegative polarization layer 312 where the negative polarization layer312 is in contact with the main pole 220 and the second layer structure314, and is magnetically stitched to the main pole 220. In one example,the negative polarization layer 312 is magnetically stitched to the mainpole 220. A notch in the main pole 220 can be created during theformation process of the spintronic device 330. In one embodiment, whichcan be combined with other embodiments, the first layer structure 311 isa bilayer and a ferromagnetic layer 313 is disposed between the mainpole 220 and the negative polarization layer 312.

In one embodiment, which can be combined with other embodiments, thenegative polarization layer 312 includes a plurality of electron energybands that includes a majority spin channel and a minority spin channel.For the negative polarization layer 312, the minority spin channelincludes a conductivity that is larger than a conductivity of themajority spin channel.

In one embodiment, which can be combined with other embodiments, theferromagnetic layer 313 includes a plurality of electron energy bandsthat includes a majority spin channel and a minority spin channel. Forthe ferromagnetic layer 313, the majority spin channel includes aconductivity that is larger than a conductivity of the minority spinchannel.

The NPL 312 includes one or more of Fe, Cr, N, Co, and/or Gd, such asFeCr, or an iron nitride (Fe_(x)N_(x)). In one embodiment, which can becombined with other embodiments, the NPL 312 includes one or moreferromagnetic materials that have a negative spin accumulation. In oneembodiment, which can be combined with other embodiments, the NPL 312includes an alloy of two materials with lattices that are oppositelyaligned, such as Co and Gd in an antiparallel alignment. The first layerstructure 311 includes a first thickness T1. The first thickness T1 iswithin a range of 3 nm to 10 nm. The first thickness T1 may be variedaccording to a diffusion length of the NPL 312. In one example, the NPL312 includes a spin diffusion length of about 2 nm. The NPL 312 includesa thickness T3 that is within a range of 3 nm to 6 nm, such as 5 nm. Inone example, such as an example where the first layer structure 311 is amonolayer, the first thickness T1 of the first layer structure 311 isequal to the thickness T3 of the NPL 312. The ferromagnetic layer 313,if includes, includes a thickness T4 that is up to 6 nm.

The second layer structure 314 includes a material that has a longdiffusion length, such as a diffusion length that is longer than thediffusion length of the NPL 312. The second layer structure 314 includesone or more layers each including one or more of Cr or Cu. The secondlayer structure 314 is a composite structure including at least twodiffering materials. In one embodiment, which can be combined with otherembodiments, the second layer structure 314 is a monolayer including oneor more of Cr or Cu. In one embodiment, which can be combined with otherembodiments, the second layer structure 314 is a bilayer and includes afirst layer 315 disposed on the NPL 312, and a second layer 316 disposedon the first layer 315 and between the first layer 315 and the STL 320.The first layer 315 and the second layer 316 each includes one or moreof Cr or Cu. The first layer 315 includes Cr and the second layer 316includes Cu. The first layer 315 includes a material having a negativeinterface polarization factor (γ), such as about −0.2. The negativeinterface polarization factor (γ) is at the interface between the firstlayer 315 and the NPL 312. The second layer structure 315 includes asecond thickness T2 that is within a range of 3 nm to 8 nm. The firstlayer 315 includes a thickness T5 that is within a range of 0.5 nm to1.5 nm, such as 1.0 nm. The second layer 316 includes a thickness T6that is within a range of 1.5 nm to 7.5 nm, such as within a range of1.5 nm to 2.5 nm, for example 2.0 nm. The second layer structure 314 isa spacer layer structure that is a second spacer layer if the firstspacer layer 390 is included. In one example, such as when the secondlayer structure is a bilayer, the second thickness T2 is equal to thethickness T5 added with the thickness T6.

In one embodiment, which can be combined with other embodiments, thefirst layer structure 311 is a monolayer including the NPL 312 where theNPL 312 is an FeCr layer having the first thickness T1, the second layerstructure 314 is a bilayer including the first layer 315 and the secondlayer 316, the first layer 315 is a Cr layer having the thickness T5,and the second layer 316 is a Cu layer having the thickness T6.

FIG. 3B is a schematic illustration of a plan view of an MFS of thewrite head 210 shown in FIG. 2, according to one implementation. Thewrite head 210 includes a spintronic device 395 between the main pole220 and the TS 240 in the track direction. The spintronic device 395 maybe used as the spintronic device 230 shown in FIG. 2.

The spintronic device 395 is similar to the spintronic device 330 shownin FIG. 3A, and includes one or more of the aspects, features,components, and/or properties thereof. The spintronic device 395includes a multilayer structure 394 that is similar to the multilayerstructure 310 shown in FIG. 3A. In the spintronic device 395, thedispositions of the multilayer structure 394 and the first spacer layer390 are switched relative to the dispositions of the multilayerstructure 310 and the first spacer layer 390 shown in FIG. 3A. In thespintronic device 395 shown in the implementation of FIG. 3B, the firstspacer layer 390 is formed between the STL 320 and the main pole 220,and the multilayer structure 394 is formed between the STL 320 and theTS hot seed layer 380. In the multilayer structure 394 of the spintronicdevice 395, dispositions of the layers 312, 313, 315, 316 are reversedrelative to the dispositions of the layers 312, 313, 315, 316 shown inthe spintronic device 330 of FIG. 3A. The dispositions of the layers312, 313, 315, 316 are such that the ferromagnetic layer 313 is disposedat a first end of the multilayer structure 394 and in contact with theTS hot seed layer 380, and such that the second layer 316 is disposed ata second end of the multilayer structure 394 and in contact with the STL320.

In the implementation shown in FIG. 3B, the directions of the currentthrough the spintronic device 395 and the electron flow through thespintronic device 395 are reversed relative to the directions of thecurrent and the electron flow shown in FIG. 3A. The current flowingthrough the spintronic device 395 flows from the main pole 220 and tothe TS 240. The electron flow flowing through the spintronic device 395flows from the TS 240 and to the main pole 220. The direction of thecurrent supplied using the current source 270 through the spintronicdevice 395 is opposite of the direction of the electron flow through thespintronic device 395.

Polarized electrons from the STL 320 are reflected off from a firstinterface 301 between the main pole 220 and the first spacer layer 390,and back toward the STL 320. Spin accumulation and spin torque occurs ata second interface 302 between the first spacer layer 390 and the STL320.

The magnetizations of the main pole 220, the NPL 312, the STL 320, andthe TS 240 in the spintronic device 395 shown in FIG. 3B are in the samedirections as the magnetizations of the main pole 220, the NPL 312, theSTL 320, and the TS 240 shown in and described in relation to thespintronic device 330 of FIG. 3A. The present disclosure contemplatesthat, depending on a polarity of the write current through a write coil(such as the coil 218 shown in FIG. 2), the magnetizations of magneticlayers (such as the main pole 220, the NPL 312, the STL 320, and the TS240) may be in a direction from the main pole 220 and toward the TS 240(as shown in FIG. 3A and FIG. 3B) or may be in a direction from the TS240 and toward the main pole 220.

FIG. 4 is a schematic illustration of a cross-sectional throat view ofthe spintronic device 330 of the write head 210 shown in FIG. 3A,according to one implementation. The layers 310, 320, 330, the main pole220, and the TS 240 can have the same cross-track widths (as shown inFIG. 3A) or may have differing cross-track widths. The layers 310, 320,330, may have differing stripe heights (as shown in FIG. 4), or may havethe same stripe heights. The layers 310, 320, 330, such as the firstlayer structure 311 and the second layer structure 314, and the firstspacer layer 390, may be tapered (as shown in FIG. 4) or non-tapered.

The STL 320 of the spintronic device 330, 395 of FIGS. 3A-B and 4 mayinclude one or more of NiFe, CoFe, CoFeNi, CoMnGe, NiCo, NiFeCu,CoFeMnGe, CoMnSi, CoFeSi, and/or other soft or hard ferromagneticmaterials, other Heusler alloys, other suitable magnetic layers, and/ormultiple layers thereof. The STL 320 can include a material havingmagnetic anisotropy oriented in any general direction, such asperpendicular, angled, or longitudinal, to the plane of the MFS. In oneembodiment, which can be combined with other embodiments, the STL 320includes a magnetic anisotropy initially oriented in the same directionas the magnetic orientation of the main pole 220 and the electron flow,as shown in FIG. 3A.

The first spacer layer 390 of the spintronic device 330, 395 shown inFIGS. 3A-B and 4 includes one or more non-magnetic conductive materials,such as Au, Ag, Al, Cu, AgSn, NiAl, and/or other non-magnetic conductivematerials, alloys thereof, and/or multiple layers thereof. The firstspacer layer 390 may be made of a material having a high spintransmissivity for spin torque transfer on the STL 320.

The second layer structure 314 is a non-magnetic spacer layer includingone or more non-magnetic materials. The first and second layers 315, 316of the second layer structure 314 include one or more non-magneticconductive materials, such as Au, Ag, Al, Cu, AgSn, NiAl, Cr, and/orother non-magnetic conductive materials, alloys thereof, and/or multiplelayers thereof. The first and second layers 315, 316 may be made of amaterial having a high spin transmissivity for spin torque transfer onthe STL 320.

The main pole 220 of the write head 210 shown in FIGS. 3A-B and 4 may beany suitable shape (e.g., trapezoidal, triangular, etc.) having suitabledimensions. The write head 210 of FIGS. 3A-B and 4 may include a leadingshield positioned on one or more sides of the main pole 220 with aleading gap therebetween. The write head 210 of FIGS. 3A-B and 4 mayinclude a side gap positioned on the sides of the spintronic device 330,395. The side gap may include an insulating material.

In FIG. 3A the track direction is labeled as the x-coordinate and thecross-track direction is labeled as the y-coordinate. The perpendiculardirection to the MFS would be the z-coordinate into/out of the X-Yplane. In FIG. 4, the track direction is labeled as the x-coordinate andthe general stripe height direction is labeled in the z-coordinate.

The multilayer structure 310 facilitates operation of the STL 320. As anexample, negative spin accumulation of the NPL 312 facilitatesgenerating direct torque on the STL 320 to facilitate spin flipping ofthe STL 320 against the field direction, and to facilitate precession ofthe magnetization of the STL 320. The NPL 312 facilitates applyingtorque to the STL 320 from both sides of the STL 320, such as both in adirection from the TS 240 and to the STL 320, and in a direction fromthe main pole 220 and to the STL 320. As an example, the negativeinterface polarization factor (γ) of the second layer structure 314enhances the negative spin polarization of the NPL 312. Such aspectsfacilitate lower voltage or lower current for the spintronic device 330,395 to facilitate reliability and effective performance of the writehead 210 while facilitating high moment-thickness product and high ADCof magnetic recording for the write head 210. Such aspects alsofacilitate modularity for various configurations of the write head 210and the materials that may be used for various components of the writehead 210, which may further lower current density and/or voltage of thewrite head 210.

Aspects of the multilayer structure 310 facilitate a reduction incritical current for flipping or switching of the STL 320 that is up to30% relative to a seed layer on the main pole 220, such as a reductionin critical current density J_(c) of up to 15%-20%, due to the increasein spin-transfer torque of the STL 320.

FIG. 5 is a schematic graphical illustration of calculated torque of anSTL versus an angle of magnetization for the STL, according to oneimplementation. The torque of the STL (normalized to critical currentdensity J_(c)) is mapped on the vertical axis and the angle ofmagnetization θ is mapped on the horizontal axis. The torque versus theangle of magnetization θ is calculated using a Valet-Fert TransportModel. A first case 501 represents a seed layer on a main pole, and asecond case 503 represents use of the NPL described herein. An increaseprofile 505 represents the increase of torque using the second case 503relative to the first case 501. As shown in FIG. 5, use of the NPL inthe second case 503 results in an increase of torque of the STL that isup to 20% over the seed layer used in the first case 501, across anglesof magnetization θ.

FIG. 6 is a schematic graphical illustration of an angle ofmagnetization for the STL versus applied current density, according toone implementation. The angle of magnetization θ for the STL is mappedon the vertical axis and the applied current density J is mapped on thehorizontal axis. The angle of magnetization θ versus the applied currentdensity J is calculated using a Valet-Fert Transport Model. Criticalcurrent density Jc is for STL switching and corresponds to the pointwhere the applied current density J is sufficient to rotate themagnetization of the STL from an initial orientation to switch or flipthe magnetization of the STL to an opposite direction that is oppositeof the initial orientation. A first case 601 represents a seed layer ona main pole, and a second case 603 represents use of the NPL describedherein. As shown in FIG. 6, use of the NPL in the second case 603results in a reduction 605 in applied current density J that is up to30%-45% less than the applied current density of the first case 601,across angles of magnetization θ. Also shown in FIG. 6, a criticalcurrent density Jc2 of the second case 603 is up to 30%-45% less than acritical current density Jc1 of the first case 601.

Benefits of the present disclosure include simple and effectivefacilitated magnetic recording performance and reliability; increasedADC for magnetic recording; reduced voltage or current while maintainingor facilitating increased moment-thickness product, magnetic recordinghead performance and reliability; modularity in magnetic recording headmaterials; and modularity in magnetic recording device designconfigurations.

It is contemplated that one or more aspects disclosed herein may becombined. Moreover, it is contemplated that one or more aspectsdisclosed herein may include some or all of the aforementioned benefits.

In one embodiment, a magnetic recording head comprises a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and a first spacer layer between the STL and thetrailing shield. The magnetic recording head also includes a multilayerstructure disposed on the main pole and between the main pole and theSTL. The multilayer structure includes a first layer structure on themain pole. The first layer structure includes a negative polarizationlayer. The multilayer structure also includes a second layer structuredisposed on the negative polarization layer and between the negativepolarization layer and the STL. The negative polarization layer is incontact with the main pole and the second layer structure is in contactwith the STL. The negative polarization layer includes one or more ofFe, Cr, N, Co, or Gd. The negative polarization layer includes aferromagnetic material, and the second layer structure includes anon-magnetic material. The negative polarization layer is an FeCr layer.The second layer structure includes a Cr layer on the negativepolarization layer, and a Cu layer disposed on the Cr layer and betweenthe Cr layer and the STL. The first layer structure also includes aferromagnetic layer on the main pole and between the main pole and thenegative polarization layer. The first layer structure includes a firstthickness that is within a range of 3 nm to 10 nm. The second layerstructure includes a second thickness that is within a range of 3 nm to8 nm. The second layer structure includes a first layer disposed on thenegative polarization layer of the first layer structure. The firstlayer of the second layer structure includes a material having anegative interface polarization factor. The second layer structure alsoincludes a second layer disposed on the first layer and between thefirst layer and the STL. Each of the first layer and the second layer ofthe second layer structure includes one or more of Cr or Cu. Thenegative polarization layer is magnetically stitched to the main pole. Amagnetic recording device including the magnetic recording head is alsodisclosed.

In one embodiment, a magnetic recording head comprises a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and a multilayer structure disposed on the main poleand between the main pole and the STL. The multilayer structure includesan FeCr layer between the main pole and the STL, a Cr layer disposed onthe FeCr layer, and a Cu layer disposed on the Cr layer and between theCr layer and the STL. The FeCr layer includes a thickness that is withina range of 3 nm to 6 nm. The Cr layer includes a thickness that iswithin a range of 0.5 nm to 1.5 nm, and the Cu layer includes athickness that is within a range 1.5 nm to 7.5 nm. The thickness of theCu layer is within a range of 1.5 nm to 2.5 nm. A magnetic recordingdevice including the magnetic recording head is also disclosed.

In one embodiment, a magnetic recording head comprises a main pole, atrailing shield, a spin torque layer (STL) between the main pole and thetrailing shield, and at least one negative polarization layer betweenthe main pole and the STL. A magnetic recording device including themagnetic recording head is also disclosed. The at least one negativepolarization layer includes a magnetic material.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A magnetic recording head, comprising: a mainpole; a trailing shield; a spin torque layer (STL) between the main poleand the trailing shield; a first spacer layer between the STL and thetrailing shield; and a multilayer structure disposed on the main poleand between the main pole and the STL, the multilayer structurecomprising: a first layer structure on the main pole, the first layerstructure comprising a negative polarization layer, and the negativepolarization layer is an FeCr layer, and a second layer structuredisposed on the negative polarization layer and between the negativepolarization layer and the STL, the second layer structure comprising: aCr layer on the negative polarization layer, and a Cu layer disposed onthe Cr layer and between the Cr layer and the STL.
 2. The magneticrecording head of claim 1, wherein the negative polarization layer is incontact with the main pole and the second layer structure is in contactwith the STL.
 3. The magnetic recording head of claim 1, wherein thenegative polarization layer comprises one or more of Fe, Cr, N, Co, orGd.
 4. The magnetic recording head of claim 1, wherein the negativepolarization layer comprises a ferromagnetic material, and the secondlayer structure comprises a non-magnetic material.
 5. The magneticrecording head of claim 1, wherein the first layer structure furthercomprises a ferromagnetic layer on the main pole and between the mainpole and the negative polarization layer.
 6. The magnetic recording headof claim 1, wherein the first layer structure comprises a firstthickness that is within a range of 3 nm to 10 nm.
 7. The magneticrecording head of claim 6, wherein the second layer structure comprisesa second thickness that is within a range of 3 nm to 8 nm.
 8. Themagnetic recording head of claim 1, wherein the second layer structurecomprises: a first layer disposed on the negative polarization layer ofthe first layer structure, the first layer of the second layer structurecomprising a material having a negative interface polarization factor,and a second layer disposed on the first layer and between the firstlayer and the STL.
 9. The magnetic recording head of claim 8, whereineach of the first layer and the second layer of the second layerstructure comprises one or more of Cr or Cu.
 10. The magnetic recordinghead of claim 1, wherein the negative polarization layer is magneticallystitched to the main pole.
 11. A magnetic recording device comprisingthe magnetic recording head of claim
 1. 12. A magnetic recording head,comprising: a main pole; a trailing shield; a spin torque layer (STL)between the main pole and the trailing shield; and a multilayerstructure disposed on the main pole and between the main pole and theSTL, the multilayer structure comprising: an FeCr layer between the mainpole and the STL, a Cr layer disposed on the FeCr layer, and a Cu layerdisposed on the Cr layer and between the Cr layer and the STL.
 13. Themagnetic recording head of claim 12, wherein the FeCr layer comprises athickness that is within a range of 3 nm to 6 nm.
 14. The magneticrecording head of claim 12, wherein the Cr layer comprises a thicknessthat is within a range of 0.5 nm to 1.5 nm, and the Cu layer comprises athickness that is within a range 1.5 nm to 7.5 nm.
 15. The magneticrecording head of claim 14, wherein the thickness of the Cu layer iswithin a range of 1.5 nm to 2.5 nm.
 16. A magnetic recording devicecomprising the magnetic recording head of claim
 12. 17. A magneticrecording head, comprising: a main pole; a trailing shield; a spintorque layer (STL) between the main pole and the trailing shield; atleast one negative polarization layer between the main pole and the STL,the at least one negative polarization layer comprising a magneticmaterial; a first layer disposed between the negative polarization layerand the STL, the first layer comprising a material having a negativeinterface polarization factor; and a second layer disposed between thefirst layer and the STL.
 18. A magnetic recording device comprising themagnetic recording head of claim
 17. 19. A magnetic recording head,comprising: a main pole; a trailing shield; a spin torque layer (STL)between the main pole and the trailing shield; a first spacer layerbetween the STL and the trailing shield; and a multilayer structuredisposed on the main pole and between the main pole and the STL, themultilayer structure comprising: a first layer structure on the mainpole, the first layer structure comprising a negative polarizationlayer, and a second layer structure disposed on the negativepolarization layer and between the negative polarization layer and theSTL, the second layer structure comprising: a first layer disposed onthe negative polarization layer of the first layer structure, the firstlayer of the second layer structure comprising a material having anegative interface polarization factor, and a second layer disposed onthe first layer and between the first layer and the STL.
 20. Themagnetic recording head of claim 19, wherein each of the first layer andthe second layer of the second layer structure comprises one or more ofCr or Cu.
 21. A magnetic recording head, comprising: a main pole; atrailing shield; a spin torque layer (STL) between the main pole and thetrailing shield; a first spacer layer between the STL and the trailingshield; and a multilayer structure disposed on the main pole and betweenthe main pole and the STL, the multilayer structure comprising: a firstlayer structure on the main pole, the first layer structure comprising anegative polarization layer magnetically stitched to the main pole, anda second layer structure disposed on the negative polarization layer andbetween the negative polarization layer and the STL.